Bio-electric stimulation apparatus has been developed for applying current pulses to a patient through electrodes located on opposite sides of the head of the patient. The current pulses at selected frequencies are applied to cause reaction with the central nervous system of the patient. Such devices, referred to as transcranial electrostimulation (TCES) or cranial electrostimulators (CES) have been used for a variety of non-invasive procedures, such as producing analgesic effects, reducing or controlling migraine headaches, and other applications of treatment and electro-anesthesia.
Earliest prototypes of transcranial electrostimulation devices originated in Russia. These original designs, although successfully employed for several different treatment modalities, had a severe drawback with regard to the comfort of the wearer or patient. In some cases, these earlier cranial electrostimulation devices even subjected the wearer to pain. It has been discovered that the reason for the discomfort of these earlier designs was a result of the use of direct current as part of the overall operation of the devices. The direct current was used to break down or lower skin resistance to allow the treatment alternating current signals to penetrate the brain and nervous systems to cause the desired effect established by the placement of the electrodes on the head of the patient.
In these earlier types of machines, the wearer received a combination of direct current and alternating current electrical waveform packages through a series of electrodes affixed to the head with straps. Typically, two electrodes comprising a cathode or negative pole of the DC based circuit would be placed approximately three inches apart to the left and right of the center of the forehead. Two other electrodes, comprising the anode of positive pole of the DC based circuit, were placed on the rear of the skull on the post mandibular area behind and below each ear.
With this DC current based design, the wearer was required to place a thick pad between any electrode and the skin. Typically, the pad was comprised of several layers of unbleached and uncolored cotton flannel, or an equivalent product. For best results, the fabric pads were soaked with water to provide a conductive path between the electrodes and the skin of the wearer. Without the presence of the pads (which were only required because of the presence of the DC current), such devices could either burn the skin of the wearer, or cause relatively intense pain before a usable level of the treatment modality of the currents at the AC frequency could be reached.
Although various types of treatment were employed by such earlier transcranial electrostimulation devices, the devices typically needed to be employed for an average time of thirty minutes per treatment period. Without the presence of the relatively thick cumbersome pads, the DC based design was unusable. With the presence of the thick padding, the DC design was bearable to the wearer, but rarely provided the wearer with a pleasant experience.
Three Russian patents which utilize such devices for different treatment methods comprise Russian patent Nos. 1489719; 1507404; and 1522500. In all of these patents, a combination of direct current and rectangular impulse current, with a frequency of between 70 and 80 Hertz, was employed at current amperages which were increased from a relatively low level to a higher or maximum level over the course of each treatment session.
An additional and potentially harmful drawback of the DC based designs was that of iontophoresis. A characteristic of a DC circuit application of this type is that molecular sized parts of metal, toxins and other undesirable impurities can be caused to migrate in the direction of current flow through the skin and into the bloodstream of the wearer of such DC based CES devices. Consequently, care had to be taken to ensure that no substance was present other than water used to create good electrical contact with the pad to the skin of the wearer. Since practically all CES treatment modalities require repeated treatments, the potential for iontophoresis being a harmful factor was escalated.
Transcranial electrostimulation (CES or TCES) originally was used in the 1960's to induce sleep; These early devices typically used less than 1.5 mA at 100 Hz. The Liss U.S. Pat. No. 4,627,438 employed higher frequencies modulated by a lower frequency squarewave to produce recurring pulse bursts. The repetition frequency of the device of Liss is determined by the modulation frequency; but the pulse bursts are of a uniform amplitude within each repetition cycle. The device of the Liss patent is specifically directed to utilization in conjunction with the treatment of migraine headaches. The low frequency or modulating signal is asymmetrical, utilizing a 3:1 duty cycle, “on” three-fourths of the time and “off” one fourth of the recurring period. This results in bursts of the high frequency signal separated by the off time when no signal is applied, following the re-application of the bursts of the high frequency signal. Some patient discomfort may be present in such an “on/off” system operation over the period of time of application of the pulse during a treatment interval.
A number of other United States patents, all directed to dual frequency systems which utilize high frequency signals modulated by a low frequency modulation carrier, operating in the general nature of the device of the Liss U.S. Pat. No. 4,627,438, exist. Typical of these patents are the patents to Limoge U.S. Pat. No. 3,835,833; Nawracaj U.S. Pat. No. 4,071,033; Kastrubin U.S. Pat. No. 4,140,133; Morawetz U.S. Pat. No. 4,922,908 and Giordani U.S. Pat. No. 5,131,389. All of these patents employ a uniform amplitude high frequency signal, which is modulated at the lower frequency of the modulation carrier.
A variation on the systems of the patents discussed above is disclosed in the Haimovich U.S. Pat. No. 5,540,736. The device of this patent employs two different current generators for providing electrical currents delivered to two electrode pairs operating across different portions of the head of the patient. This allows independent control of the current generators to administer independent regulated electrical current across each of the pairs to adjust for different impedances caused by the physiological and anatomical differences between different sides of a patient's mid brain portion, the quality of the conducting medium, and other factors. In all other respects, the system disclosed in this patent is similar to the operation of the system disclosed in the Liss patent discussed above.
Russian patent publication No. 2139111 is directed to a method for treating narcomania, which is a treatment also used in others of the CES patents described above for alcohol and narcotic addiction. In this patent, transcranial electrical stimulation is accomplished by means of packets of current with a duration of four milliseconds, at a modulation frequency of 100 Hz. Within each of the packets, the high frequency signals have a uniform frequency and current amplitude.
It is desirable to provide a transcranial electrostimulation apparatus and method which overcomes the disadvantages of the prior art, and which has increased effectiveness and increased user comfort.